(1) Field of the Invention
The present invention is directed to reduction in the emission of highly toxic volatile products, such as methyl bromides or iodides or ethylbromides or iodides, during the cure of fluoroelastomers with peroxides.
(2) Description of the Related Art
The cure with organic peroxides of the fluoroelastomers containing, as cure sites, bromine or iodine atoms along the polymeric chain and/or at the end of same is well known. In said fluoroelastomers, bromine or iodine are introduced into the elastomeric macromolecule by using, in the polymerization step, brominated or iodidated comonomers such as in particular fluorobrominated olefins, brominated or iodidated fluorovinyl ethers, or by using in the polymerization brominated or iodidated compounds such as chain transferors.
In the peroxide cure, use is generally made of organic peroxides of the aliphatic or cycloaliphatic type, or saturated or unsaturated alkylaromatics, such as for example:
2,5-dimethyl-2,5-di(ter.butylperoxy)hexene-3 PA0 2,5-dimethyl-2,5-di(ter.butylperoxy)hexane PA0 dicumylperoxide PA0 ter.butylperbenzoate PA0 ethyl-3,3-di(ter.butylperoxy)butyrate PA0 1,1-bis(ter.butylperoxy)3,3,5-trimethylcyclohexane
which give rise, in the cure process, to the formation of methyl or ethyl radicals. These radicals, when combining with the bromine or iodine contained in the fluoroelastomer, can give rise to the above-mentioned methyl or ethyl bromides or iodides, which are highly toxic and probably also cancerogenous volatile products.
Therefore, while the cured articles produced by means of peroxide cure of fluoroelastomers containing bromine or iodine exhibit excellent properties and characteristics at least partially higher than those of the fluoroelastomers cured by means of iones, the peroxide cure of the abovesaid products involves a serious hazard for the health of the operators and espress prohibition of such processing in the next future from the competent authorities is considered as possible.